Checking Exhaust System Backpressure
- Check exhaust system with either a vacuum or pressure gauge. Remove O2 sensor.
- If using a 1-10 psi pressure gauge, operate engine at 2500 RPM. If exhaust system backpressure is greater than 2 psi, exhaust system or catalytic converter is plugged.
- If using a vacuum gauge, connect vacuum gauge hose to intake manifold vacuum port. Start engine and observe vacuum gauge. Open throttle part way and hold steady. If vacuum gauge reading slowly drops after stabilizing, check exhaust system for restriction.